An application for guiding a pedestrian to a destination has been conventionally proposed. For accurately guiding the pedestrian to the destination, it is necessary to grasp the position of the pedestrian in real-time with high accuracy. As a positioning technique that measures the position of the pedestrian, a GPS (Global Positioning System) technique in which radio waves from a satellite are received with a terminal carried by the pedestrian is popular. However, because the terminal cannot receive the radio waves from the satellite indoors, for example, in a station building or an underground shopping mall, the positioning by the GPS cannot be used. Therefore, as a technique for achieving guidance of the pedestrian indoors, a relative positioning technique using a self-contained sensor such as an acceleration sensor, an angular velocity sensor, or a magnetic sensor, has been proposed. The relative positioning by means of the self-contained sensor is achieved, for example, by detecting the movement of the pedestrian by the self-contained sensor, estimating a travelling direction and a traveling velocity, and calculating a vector of the movement of the pedestrian.
However, the self-contained sensor (especially, a gyro sensor (angular velocity sensor)) has to be regularly calibrated because a bias noise is always changed by disturbance such as the temperature. Such techniques are described in Patent Literatures 1 to 4, for example. Patent Literature 1 decides a technique of deciding a state in which the pedestrian stands still from the movement of a pedestrian and correcting the gyro bias during a period in which the pedestrian stands still. Patent Literature 2 describes a technique estimating the traveling direction of the pedestrian from a map and correcting the gyro sensor. Patent Literature 3 describes a technique of calculating the traveling direction of an automobile from the gyro sensor and, in a case where the amount of change in the traveling direction is equal to or less than a threshold value, correcting the gyro sensor while regarding the traveling direction of the automobile extends along a straight line. Furthermore, Patent Literature 4 describes a technique of estimating the position of an automobile using a white line or a road sign observed from the automobile as a reference.
Patent Literature 1: Japanese Patent Application Re-publication No. 2010-001968
Patent Literature 2: Japanese Patent No. 5059933
Patent Literature 3: Japanese Patent Application Laid-open No. H07-324941
Patent Literature 4: Japanese Patent No. 4897542